Q. Recently, I saw a familiar photo used in a decking manufacturer’s ad — it was one that I took of a deck I had built! I didn’t tell anybody they could use my pictures. What can I do about this?

A. Diana Hanson, a paralegal specializing in intellectual property, responds: Before you do anything, determine whether it is unauthorized use. For example, if you submitted your photo as part of a competition or an online invitation, you may have actually given permission — check the fine print.

Once you determine that it really is unauthorized use, keep calm. You will accomplish more by being reasonable and businesslike than by being emotional. Think about what you want the end result to be. If you want monetary compensation, figure out how much. If you want a “photo courtesy of …” credit, create the wording. Maybe you just want them to acknowledge that they messed up, and to promise to ask you next time.

When you’ve determined what your goal is, make contact with the offender. It’s easier if you have a connection — you might know a sales representative or an editor that you can start with. That person may be able to help you directly or put you in contact with the right person or department.

In simple terms, explain that your photo appeared in the company’s advertisement, and you didn’t authorize it. Then explain how you want the situation resolved. Get all the contact information of the person you speak with. Set a time frame for when you can expect a reply.

Follow up your phone call with an email or a letter, summarizing the phone call. Then wait the allotted time. If someone gets back to you and is willing to work with you, great. If not, move on to the next step.

Send a more stern email or letter to the person you were in contact with, and send a copy to someone higher up, as well as to the sales representative or editor who is your usual contact. You might also send a copy to an attorney. Use a “cc:” at the bottom of the letter to let the offender know that you are sending copies to other people. If you decide to copy an attorney with the correspondence, you should call her office first and ask permission, or you will get a bill. You might get billed anyway, so clear that up in the phone call. Indicate a time limit for responding in this letter. If you hear back within that time frame, great. If not, it might be time to hire that attorney.

Use of your photograph falls under copyright law, a complicated area of intellectual property law. A general practice attorney might be able to write up a good cease-and-desist or demand letter for you, but if you end up moving toward litigation, get an expert. When the offender receives a letter about your photo on law-firm letterhead, she will probably pay attention. Understand, however, that by hiring an attorney, you will have escalated the matter, and the other side will have its attorney talk to your attorney only. No one will communicate with you except through your attorney.

Hopefully, at this point you will get some kind of resolution to your problem. If not, and you really want to make a stand, you are going to have to sue for copyright infringement.

It gets a little tricky here. If you have registered your photo with the U.S. Copyright Office, you can sue for statutory damages up to $150,000 for willful infringement, and include attorney fees. If you do not have a registered copyright for your photo, your ability to recover is limited to actual damages only. Actual damages are usually determined based on industry standard for licensing fees, which may not be worth the bother.

For future reference, copyrighting photos that you are going to publish is a good idea. It’s not complicated or expensive. You can go to copyright.gov for the forms and instructions to file a copyright. In order to recover the statutory damages referenced above, you must copyright a photo within three months of first publication or three months prior to infringement.

It’s also a good idea to watermark all of your photos with “Copyright, (your company name, year)”; for example, “Copyright, Best Decks in the Universe Inc., 2012.”

Diana Hanson is a co-owner of Woodpile Products and Woodpile Construction in Meridian, Idaho.